US2014606A - Three-color film and process - Google Patents

Description

Sept. 17, 1935. D. K. ALLISON 2,014,606

THREE-COLOR FILM AND PROCESS Filed May 12, 1934 Fig.1." PRINTING LIGHT. Pnmmls 1.161411% ore-memes. PAN-NEG I mama EMUL.B H YIIIIIIIIIIIIIIIIIIIIIIII/fi BASE Q b \0 mm: BASEW /1 W nruo mze' PAN. NEG. 0

' @mmrme LIGHT. PRINTING'LIGHT MATRIX PROCEDURE .A. MATRIX nocznun: B.

YPRIMI nupnor PRINT, DEVELOP MAKE PRINT om'no. nregmrfi AND FIX POSITIVE" FROM .PANNEGATIYE DEVELOP AND rlx COLOR EMULSION SuPERPosI-Z Pmm' B BLUE FROM comm/mom PRINT REVERSE rcu COLOR EMULSION DEVELOP mm FIX v A RED WASH AND DRY.

, REVERSE ETCH. I W'ASH, FIX, WASH 1 AND DRY POSITIYE ASH HND DRY I I PREPARE MATRIX L BY PROCEDURE '-A OR B IMPREGNarE MATRTX' WITH YELLOWDYE IMBIBE YELLOW IMAGE 0N POSITIVE ATTORNEYS.

tamed Sept. 17, 1935 PATENT err-Ice 2,014,606 THREE-COLOR, FILM AND PROCESS Donald Allison, Beverly Hills, Calif. Application May 12,, i934, Serial No. 725,311

6 Claims.

This invention relates in general to color photography and finds its most-valuable application in the'field of motion pictureproduction,

although it may be applied with equally efl'ec- 5 tive results to still photography. Whenever the term film is used, it is to be understood that it comprehends all types thereof, including. plates,

film for still work, film for motion picture work and all other types of photographic media. However, inasmuch as my invention finds its chief application incinematography, I will illustrate a preferred and modified form thereof in this connection without however, limiting myself thereto-.

Numerous processes, have been evolvedfor the making of motion-pictures in color and they have more or less divided themselves into two main classes known as additive and subtractive. The

production of negatives by subtractive processeshas in turn been divided into the niulti-p'ack system, thecommonly known being bi-pack, and

the light-splitting of separating method. As to Another object of my-invention is three-color process that can be readilyadapted the production of positive prints, it has been divided into photographic printing and photomechanical or imbibition printing, depending on how the positives are produced from the color separation negatives.

For the production of negatives, my invention preferably employs the,bi-pack system because of its simplicity and economy of operation, although the' light splitting or separating system can be used, just so long as accurate color separation is obtained; In the production of positives by my process, I utilize in the preferred forms thereof both photographic and photomechanical printing to secure a three-color positive from but two original negatives.

It has long been the aim of all research workersin the field of color photography'to produce accurate three-color rendition by using but two negatives, and it is an object of my invention to produce suchth'ree-color rendition in positive prints by the use of but, two negatives. So far as I am aware, this has never plished satisfactorily.

. It is also an object of my vention to-provide a' color process that will attain this result accurately, while being at the same timev relatively simple andeconomical in operation-and positive in its reproduction 'of colors. a

to provide a.-

to existing two-color processes so that by a comparatively slight modification of existing twobefore been accomcolor laboratories, they can be made capable of producing satisfactory three-color prints. A further advantage being that no change in cameras or photographing technique is needed to accompany such a plant change-over.

Other objects and advantages of my film and method of making the same will become apparent from the following description of a preferred form and modification thereof.

In the attached drawing: I

Fig. 1 shows a preferred form of positive film being printed photographically from two colorseparation negatives.

Fig. 2 shows a modified form of positive film being printed. Y

Fig. 3 is a chart showing the steps of preferred form of the entire process and two difierent pro-' cedures for securing the matrix.

As previously mentioned, I prefer to use the bipack system of securing color separation nega- 20 tives, which system consists briefiy in running two films through the camera gate face to face. The outside negative or the one on which the light first impinges may be of the type usually designated in the trade as orthochromatic, and is sensitive to substantially the blue to green range of the spectrum only. I will term this negative hereafter the "front" or ortho" negative. After the light impinges on the front negative, it passes therethrough onto the second or rear negative which is known as a panchromatic mm and is sensitive to substantially all colors but predominantly to the orange to red end of the spectrum. This negative I will hereafter speak of as the rear" 'or fpan" negative. r

Dueto the fact that the rear negative is sensitive to all colors, it is necessary to filter out all blue light passing through the front negative before it strikes the rear negative. This can be readily accomplished by dyeing the front negative with a substantially orange-red surface dye such as diphenyl-disazo-bis-a-naphthyl-amine- 4-sulphonic acid, known generally as Congo red or the like which will .allow a slight amount of green and the yellow and red rays to reach the 45 rear film. Bi-pack fllm'of this general type with a'red filterdye in the ortho' negative is readily available on themarket under various trade j names- After exposure of the two negatives they de- 60 veloped and fixed by any of the well-known methodsand the red filter dye washed out of the front negative. From 'the foregoingit will be evident that'the front negative carries a silver image-recording the blue to green colors of the objects photographed and the rear negative carries a silver image of the green to red colors of the objects,

it being noted that the green is recorded on both front and rear negatives.

.Various processes are now known and commercially available for producing two-color positive prints from such color value negatives, one.

of the simplest and most effective being to photographically print the two negatives in registry to opposite sides of a double-coated positive film and then tone, dye, or dyetone the side of the positive printed from the ortho negative red, and then tone, dye, or dyetone the side of the positive printed from the pan negative blue. This gives a very satisfactory product for two color rendition,

but, of course, using but two primary colors the Blue tone Ferric ammonium oxalate 9 grams Potassium ferricyanide 5 grams Ammonium chloride... 11 grams Hydrochloric acid 6 c. c. Water 1000 c.c.

Uranium tone Uranium nitrate 9 grams Potassium oxalate 6 grams Potassium i'erricyanide 7 grams Hydrochloric acid 8 c. c.

Water 1000 c. c.

If desired, I can produce the two color positive by employing what is known in the art as the iodide bleach process by which method one side of the film to be colored is first bleached with a solution such as:

Iodine 15 grams Potassiumiodide -r. g 60 grams Acetic acid 25 c.c. Water 1000 c.c.

and then subjected to a basic red or blue dye, depending on which side is treated, which said dye is mordanted on the iodide image. The other side ofthe film can then be treated in a similar manner or can be toned with'iron or uranium as pre- 'vioushze'xplained to secure a blue or a red image as needed. Likewise a copper toning solution can be used for coloring the red side of the film which can be amplified, if desired, by an additional treatment with a basic red dye which is mordanted by the copper image. A suitable copper 1. tone and mordant is:

There are, of course, numberless methods of producing a two color positive by photographic printing and subsequent toning, dyeing or dyetoning, each with its proponents and each having certain advantages. The particular method of accomplishing this first step of my process forms no part of my invention except that it shall be one which will give sumciently transparent I images for commercial projection use,

from by any suitable method as just explained, I 5

prefer to proceed in one of two ways to build up my two-color print into a three-color one. In that one of these, preferred procedures is more simple to perform than the other, I will refer to it as procedure A, describing it first, although it will 0 be understood that the second procedure, referred to herein as procedure B while being a little longer, gives the better results.

In carrying out procedure A, I produce a matrix from the ortho negative by making a dupli- 15 cate or dupe of the ortho negative by-making a print therefrom on ordinary positive duping stock, producing what .is termed a lavender or duping print, and then making a print from the lavender print which will, of course, be a negative go of theobject photographed.

I then treat the dupe negative with an etching solution which can be made up substantially as follows:

Hydrogen peroxide (3%) 30 c. c. 25 Cupric sulphate 20 grams Nitric acid (conc.) 5 c. c. Potassium bromide 0. 5 grams Water. 1000 c. c. 30

'us' a relief image recording the yellows and reds, 40

and a portion of the greens.-

Using the relief image film as a matrix, a yellow, preferably acid, dye is impregnated into the gelatin of this matrix, and from this a yellow image isthen imbibed or photomechanically 5 printed in registry on one side of the two color print already obtained. In practice I have folmd it preferable to imbibe the yellow image on the red side of the two-color print, although it can be imbibed on the blue side of the print, if de- 50 sired. r The effect of imbibing the third color, yellow, onto the two-color print is to give us full range reproduction of the visible spectrum. While the yellow dye is actually applied to the yellow, 55 orange and red images, the effective result is that the portion which is represented yellow, comesout yellow for the density of. theimage beinglow, the amount of red coloring is small,

'sothat the yellow .dye imbibed thereon predomiw and blocks out the red. As to the orange which is a little heavier density than the yellow,

5' the only eifect of imbibing a yellow dye thereon is to brighten it up and make it a truer orange. The fullredportion of theimagewhiehisthe heaviest density is not affected appreciably bythe application of the yellow dye. The result then is that we have yellows, oranges and reds faithfulLv reproduced on the side of the positive printed from the ortho negative and previously 70 colored red.

As before mentioned, the greens are recorded on both front and rear negatives and it was noted that in printing, the greens were therefore printed'on each side of the positive, andatthe end of the first step of my process were-formed ,or a thin blue image on one side of the print and -a very thing orange image on the oppositeside thereof in registry with the blue image. As my matrix formed from the dupe ortho negative records greens to a slight extent, it will, of course, .imbibe yellow dye on that portion of .the light orange colored positive which is supposed to be green and then the resultant yellow image in' combination with the blue, will reproduce a true green when projected on the screen.

I In practicingmy second or alternative method, I produce a matrix from ,the pan negative for imbibing the yellow image, This method, which I term procedure B, is as follows;

The pan negative is printed onto ordinary black and white positive stock and then without developing up the latent image thusobtained, the uncolored print previously made by printing in registry to opposite sides of a double coated positive, is used to superpose a print on the 1111 developed print made from the pan negative! The superposed latent images are then developed,-

-up and fixed in the usual manner.

The composite print thus obtained is then reverse etched by treatment with a suitable solution such as the one previously mentioned, to produce a matrix composed of a gelatin relief image substantially similar to the matrix formed by the first method described. There is, however, one essential difference and advantage .of this second matrix over the one made'from the ortho-negative, namely, that in this second form of matrix only the greens, yellows and reds are in relief, the blues, grays, whites and blacks being washed out, whereas in the-first matrix the grays and blacks are also in relief as well as the greens, 1

yellows and reds. I have found that in the process first described'imbibing yellow on the blacks 40 does not appreciably affect them, i. e., black by this process is made from red and blue, with an allowance for the addition of yellow. However in the case of the grays the addition of the yellow is sometimes noticeable and has a slight tendency to' give them a. muddy effect.

- The color balance maintained between the red and the blue will," of course, depend on which type of matrix. is employed, for if type A is used, blacks are the subtractive result of blue, red

and yellow, whereas, ifv type B matrix is used, blacks are the subtractive result of red andblue only.

While I have deemed it necessary to describe in detail only two methods or procedures for producing a suitable matrix for use in my process, it is to be understood that I do not limit myself to these two forms shown, as my invention in its broad aspect comprehends a three-color print formed by the addition of a third image by imbibing from any suitable matrix. obtained by the use of one or both of two color-separation negatives, on to a two-color print previously produced from said two color-separation negatives.

paring matrices which are eminently satisfactory for this-work. Some of these methods are for example, the bichromate process, in which the.

gelatin carrying a silver image, when treated with bichromate, becomes insoluble in hot water There are various other known methods of pre- 5 cause insolublization of the gelatin contiguous to the image.

I cite these various methods of making matrices .to show the'wide range of operations by which .my invention may be practiced. It should 5 be noted, however, that the above lastly described relief processes yield images negative in reliefto the previously described etch-out process, and the matrices would therefore be obtained fromimages negative to, i. e., printed from, that specified for it) the etch-out process.

While I prefer to use double coated or duplitized positive stock, my process is readily adapted to use a film having one extra thick emulsion only,

or two emulsion layers on the same side of the 15 support. The only variation in my process as applied to this type of film is in the first step; namely, the production of the initial two-color print. One method of securing a satisfactory two-color printv on such film is to print both 20 negatives as before, one to the face of the posi-' .tive, stock and one through the base to the inside of '{the emulsion. After developing and fixing both images, the film can then be immersed in a bleaching solution such as an iodidebleach or 25 fcrricyanide bleach and left until the outer image has been completely bleached. The film is removed before the inner image is affected and the .excess bleach is washed out. The film may then be immersed in a solutionof basic dye which will 30 mordant to the'bleached image but will not affect the inner image. After this step the film is sub-i jected to a toning solution of a color substantially complementary to the dye previously used, which tones the inner image the desired color without 3 afiecting the previously dyed image.

Another way to produce the two-color print on this type of stock is to immerse -'the film with the developed image in a solution of iron tone until the outer image is fully converted to a blue 40 color and then to quickly remove the film and V wash out theexcess blue tone to keep it from affecting the inner image. The film can then be immersed in a uranium toning solution to color the inner image red, the uranium tone not affect- 45 ing the previously iron-toned outer image.

When in the foregoing ,I use the term threecolor as applied to a processor print, it is to be understood that I mean a process employing three-oblors'in its operation, or a print secured by such a process, and I do not mean to imply that the print reproduces but three colors, for it is well known that by the proper combination of three primary colors all colors of the visible spectrum can be obtained.

Also, when in the claims I use. the phrase superposed emulsions it is to be understood that I include emulsions with and without a separating layer between them.

From the foregoing it will be seen that I have inno wise as limiting the proper scope of my invention as defined by the appended claims.

. I claifn as my invention:

1. The method of producing a photograph in color which includes: producing two substantially complementary color-value images in superposed emulsion layers; coloring said images red and blue respectively; and imbibing a yellow dye image of the green tored color values of the same subject on top of one of said first mentioned images.

2. The method of producing a photograph in color which includes: producing a blue to green color-value negative and a green to red colorvalue negative; producing positive images from said negatives in superposed emulsion layers; coloring the positive image produced from the green to red color value negative blue; coloring the positive image produced from the blue to green negative red; producing from one of said negatives a matrix having a green to red color value relief image; applying a yellow dye to said matrix; and imbibing a yellow image on one of and green to red color-value images in separate emulsion layers on opposite sides of a support; toning said first image blue; coloring said second image red; and imbibing a third image on one of 'said emulsions. by impressing thereon a matrix 5 having a green to red color value image of the same subject carrying a yellow dye.

5. The step in a three-color photographic process which includes: making a matrix for use therein, by producing two substantially com- 10 plementary color-value negatives; making a combi-ned print of said negatives; making a separate print of one of said negatives; superposing on said separate print a print from said combined print; developing and fixing said superposed l5 printed images; and treating said film to remove the silver images and the contiguous gelatin therefrom to give a gelatin relief image.

6. The method of making a matrix for use in a three-color process of photography which in- 20 eludes: producing a blue to green color value negative and a green .to redcolor value negative; printing said negatives to opposite sides of a double coated film to give corresponding positive images; making a positive image from the green 5 to red negative only; superposing on said image an image printed from said double coated film; developing and fixing said superposed images; and treating said images to remove the silver and the contiguous gelatin therefrom to give a gelatin 30 relief image.

DONALD K. ALLISON.

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